Chainsaw sharpener



FIG. 1 is a front-top-right perspective view of a chainsaw sharpener, showing my new design;

FIG. 2 is a front-top-left perspective view thereof;

FIG. 3 is a front view thereof;

FIG. 4 is a back view thereof;

FIG. 5 is a left side view thereof;

FIG. 6 is a right side view thereof; and,

FIG. 7 is a top view view thereof. 

CLAIM The ornamental design for a chainsaw sharpener, as shown and described. 